"The only thing that's changed is everything," says Apple in its TV ads for the iPhone 6S. But in day-to-day use, I've hardly noticed any meaningful differences. The fact that it looks completely identical from the outside doesn't help.

Sure, the cameras are better, photos can now "come alive," and 3D Touch lets you access shortcuts and new menu options for your apps. But these features have had a minimal impact on how I actually use my phone.

Here's what I think of all of these new features:

The cameras. Both front and rear cameras offer more megapixels to capture more details in your photos. But you won't notice much of a difference in photo quality if you mainly view all your photos on your iPhone, like I do. (You'd probably notice the differences more if you ported those images to a larger monitor.) Selfies do look considerably better, but I'm personally not into selfies.

Live Photos. This is probably my favorite new feature. I'm not a huge photo-taker, but I do love that I can swipe or touch these photos to see moments play out before and after each shot was taken. It really helps photos feel more like living memories instead of pixels frozen in time.

3D Touch. Despite being a pretty nifty trick (and an addicting behavior), 3D Touch is not all that useful just yet. Most apps don't work with 3D Touch, and they create unpleasant feedback when you try to press into them. As for the few apps that do support 3D Touch, those work quite well. Being able to immediately get directions home in Maps, for instance, or launch your camera's selfie or video recording modes is pretty neat. But at most, 3D Touch is only saving me one or two extra taps. Some apps, like Apple's Mail app, don't actually save me any time using this feature. "Peek" and "pop" in Mail is just a substitute for tapping on a new email, but it's no more efficient. It's fun to use, but it doesn't feel like a game changer right now.

To me, using the iPhone 6S feels no different than using the iPhone 6. The biggest change is not 3D Touch, but all the new camera features, so your opinion of the phone will likely depend on how often you take pictures or notice minute details in your shots.

Upgrading from the iPhone 6 didn't feel worth the price of admission for this new phone. At the same time, I would love this phone if I'd upgraded from an iPhone 5S or earlier. If you missed out on the iPhone 6, this is just a tad more refined and a little more snappy: One great example is Touch ID, which is significantly faster at recognizing your fingerprint, getting you into your phone almost instantly.

In general though, the iPhone 6S feels like the most modest "S" iPhone upgrade yet. The new features are cool at best, but only moderately useful. If you own an iPhone 6, you're not missing much if you choose not to upgrade. Unless you plan on changing the size of your phone — upgrading to a bigger screen, for instance — don't spend your money this year. Wait until the iPhone 7.